


Just For Tonight

by FandomsMayChange



Category: Undertale (Video Game)
Genre: Adult Frisk, Alternate Universe - Underswap, Frisk talks him through it, Gender-Neutral Frisk, Gender-Neutral Pronouns, Ghost Frisk, Masturbation, Mutual Masturbation, Other, Sexual Frustration, Shameless Smut, as i always write for frans, biologically female Frisk, for a little while, idk what else to tag this garbage as, maybe something not porn some day lmao, sans is innocent
Language: English
Status: Completed
Published: 2018-01-23
Updated: 2018-01-23
Packaged: 2019-03-08 14:43:00
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings, No Archive Warnings Apply
Chapters: 1
Words: 1,537
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/13460412
Author URL: https://archiveofourown.org/users/FandomsMayChange/pseuds/FandomsMayChange
Summary: Sans had been feeling very strange and frustrated for a few days, so he asks Frisk for help.





	Just For Tonight

**Author's Note:**

> :')
> 
>  
> 
> i love me some swap!frans

Sans was tossing and turning in bed all night. He never needed sleep, but he's felt weird for a few days. In the end, he decided to give it a try. It worked for a while, but tonight he feels more bothered than ever.

Sans rolled around on top of the covers and groaned. "Wh- what is going on..." His cheeks were hot and he felt strange in places he had never felt before. He loosened the scarf from around his neck and tossed it to the side, hoping to cool off. But nothing seemed to help. He clutched his chest and thought for a moment. "Fr- Frisk?" He quietly called out.

Within seconds they appeared before him. They looked rather annoyed as they hovered over him. "What?" Their voice was soft despite them trying to sound mean.

"C- can I ask you something?"

They huffed and flew closer to Sans. "Are you sick or something? Your face is all blue."

"Um... I'm not sick... That's actually why I called you here. I feel too embarrassed to ask anyone else." He looks away.

Frisk crosses their arms. "Alright, what's the problem?"

"W- well... Every night for these past few days I've felt very strange." He rubs his head. "Like, my face is all hot. I feel weird in..." He gestures towards his shorts. "That area... And it's just getting worse... I don't know what to do."

Frisk stared at him with wide eyes before laughing loudly. "Seriously?!" They laughed so hard their face turned red. "I am so glad you're the only one who can hear me!"

He blushed harder. "H- hey..." He crossed his arms. "Don't laugh at me..."

They wiped away a tear and settled down. "Alright, alright..." They looked at him and floated closer. "Sans..." They smiled. "You're horny."

"Wh- what?" He looked confused. "What's that?"

"You want to be pleasured, sexually."

His eyes went wide and he covered his face. "What?! No! I- I am sick! You were right!" He starts to fake cough.

"Sans, don't hide it. It's only natural. For humans and monsters. You just need to..." They made a motion at their crotch. "Rub one out!"

Sans shook his head. "Why this? Why this?" He slightly uncovered his face. "I don't even know where to begin..."

"Well first, you need some stimulant! Think of something sexy with someone you like!"

Sans tried to think of something but shook his head. "I can't..." He whined. "I've never thought of anyone like this..."

They rolled their eyes. "That kind of makes things difficult..." They think for a moment. "Um..." They blushed. "Y- you can use me if you'd like..."

"Huh?" He looked away. "If you're okay with that... But I can't even touch you."

Frisk blushed harder. "You don't need to touch me, nor would I ever let you..." They pulled their sweater up slightly, revealing their soft pudgy tummy. "You don't need to touch... Just look. I can help you get going..."

Sans stared at Frisk with stars in his eyes. "Looks so squishy..."

Frisk let out an annoyed groan and looked away from him. "Sh- shut up!" They pulled their shirt up a bit more to show their breasts. Frisk was very medium in that area. "This doin' anything for ya?"

Sans continued to stare at them with longing eyes and nodded slightly. "Y- yeah..." He sat back when he felt something pressing against his shorts. "Wh- what?" He looked down and saw something glowing.

Frisk looked at him again. "Is this seriously your first time? Were you never a teenager?"

"It is..." He pouted. "I've never felt like this before."

"Geez... I... I'll walk you through it, okay?"

He nods and pulls down his shorts slightly to see. "Oh!" A glowing blue member stuck up before him.

Frisk stared at Sans as he started figuring things out. "Really pissed my body isn't corporeal right now..."

Sans touched his member and shuttered before looking up at Frisk. "What'd you say?"

"N- nothing!" They looked away again. "J- just wrap your hand around it and move your hand up and down. Start off slowly."

"Oh, um... Okay." He did as he was told and shivered. "This... I... I've never felt anything like this before..." He looked up at Frisk.

"Mmhmm..." Frisk was gently squeezing their own boobs. "That's how it usually is." They pinched their nipples gently and started squirm.

"Oh... Y- you're doing things too..." He let out soft moans as he moved.

"Duh... I'm not just going to sit here and watch..." They listened to his voice and sighed.

"O- of course not. I'm glad you're doing it too." He smiled. "You're nice to look at..."

Frisk could barely handle the things he was saying. "St- stop it!"

"I'm sorry, I'm sorry..." He leaned back and continued to watch Frisk.

"You can speed up whenever you feel you should." He nods and they watch him move faster. Frisk thought for a moment before taking off their sweater and pants completely. They spread their legs open and rubbed their clitoris before him.

"A- ah!" Was all Sans could manage as he watched.

"Sans..." They breathed. "J- just keep going..."

He nods and does just that. "F- feels s- so good..." He clings to the bed with his free hand and continues to watch Frisk.

Soon Frisk started to softly moan as well. "S- Sans... Whoever you're thinking about..." As if they didn't already know. "Call out their name whenever you feel it."

"F- feel it?"

They moaned as they started to rub faster. "You'll know..."

Both of their breathing had increased significantly and the sound of quiet moaning filled the air. The two continued to watch each other please themselves. Frisk observed that Sans was really enjoying himself from the way he looked at them. Though they both still wanted more than they could get.

"Sans... I- I really wish I could touch you right now... I want to feel you inside me..." Frisk whined. "This is so unfair..."

"Me too Frisk... I want to touch you and squeeze every part of your body. You look so beautiful..."

"Sans..." They covered their blushing face. "That's embarrassing..."

He didn't respond for a moment. "B- but it's the truth..."

They smiled. "You know you look really good doing that... Even if you are a skeleton. I could watch you all night..."

He moaned out a bit louder than usual and Frisk smiled a bit more. Their exchange of compliments went down as they got closer to their limit. The both of them were getting a lot louder than before. Sans couldn’t be as loud and struggled to keep his cool.

"Frisk! I- it feels so good... S- something's building up..."

They struggled to speak back because the same thing was happening to them. "We- we're climaxing soon..."

Sans wasn't entirely sure what that meant but nodded anyway. He let out another moan. "Fr- Fri-" He covered his mouth. He remembered what they said, but he was just too embarrassed.

Frisk looked at him and floated over him, still touching themselves. They were now face to face. "Say it."

"Wh- what?" He whimpered.

"Say it. Say my name. I know you want to." Their expression was very needy as he looked at them.

"Fr- Frisk..." He moaned quietly.

"Louder."

He started removing his hand even faster. "Frisk!"

"Louder!"

"Frisk!" He shouts a bit now. "Frisk!"

"Yeah... That's what I like to hear..." They closed their eyes. "S- Sans... I- I'm about to cum..."

"Frisk..." He looked at them with half-closed eyes. "Something's coming...!"

At nearly the same time the two started loudly moaning together. Sans called out Frisk's name a little bit too loudly as he released his load. In return, Frisk moaned his name several times as a wave of pleasure was sent through their whole body.

They both slowly opened their eyes and tried to catch their breath. They stared at each other for a moment, not sure what to say.

Sans looked away. "M- my shirt is messed up..."

Frisk snorted then started laughing. "Seriously?! That's all you have to say?"

He twiddled his fingers together and looked away. "I- I didn't want to say anything weird..."

"Did you have something in mind?" He nodded and they smiled. "Then say it."

He looked around the room and didn't speak for a minute. "I- I had a lot of fun." He looked up at them. "I really like your body and... And I want to do this again."

They chuckled. "We can do this as often as you'd like."

"A- also..." He spoke really quickly. "I love you."

Frisk tilts their head. "Hm?"

He covers his face. "I love you! I have for a while now... I was just too nervous to say anything..."

"Aw..." Frisk clasped their hands together and twirled in the air. "That's so cute!" They moved back in front of him and smiled. "I- I love you too."

He smiled. "That makes me so happy!" He looked at Frisk before getting under his covers. "C- can you stay with me until I fall asleep tonight?"

They snapped their fingers and all their clothes were back on. "Sure."


End file.
